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Operations CXO Status Report

Friday 5 July 2013 9.00am EDT

During the last week Chandra completed the observing schedule as planned.

On Jun 28, following the execution of a real-time procedure to perform a reconfiguration of the battery reconditioning resistors, the configuration of the resistors on Battery 2 was reverted by the On-board Computer (OBC) flight software to the previous state. This was an unanticipated side effect of the software processing when the full-charge current for Battery 3 dipped below the flight software threshold and the EPS Charge Current Monitor tripped.

Real-time procedures were executed on Jun 28 to dump OBC-A memory as a follow-up to the flight software patch earlier that day. On Jul 1 a real-time procedure was executed to dump a portion of OBC-A memory as part of the effort to investigate the Battery 2 resistor reconfiguration.

On Jul 2 a real-time procedure was executed to patch the EPS Current Monitor Threshold to a new lower value which is consistent with trending expectations for the battery full-charge current. This is in response to the expected efficiency drop of the solar arrays due to aging. A second real-time procedure was used to reconfigure the battery reconditioning resistors for Battery 2 to adjust the battery trickle charge current. This accomplished the original goal of the real-time patch procedure on Jun 28. A third real-time procedure was executed to re-enable Battery 3, which had been disabled as a result of the EPS Charge Current Monitor tripping on Jun 28.

Real-time procedures were executed on Jul 2 and Jul 3 to dump OBC-A memory as a follow-up to the flight software patch. The dump will be used to update the baseline memory image maintained on the ground.

Finally, a real-time procedure was executed on Jul 3 to perform a routine self-check of the Electrical Interface Assembly (EIA) Sequencer.

Of note this week was the release of CALDB 4.5.7. This includes ACIS time-dependent gain corrections for the period Feb - Apr 2013, ACIS blank-sky background files covering time after 2009-09-21, and correction to HRC-S time-dependent gain maps. For details see:

The schedule of targets for the next week is shown below and includes a TOO observation of SN2013df:

        Radiation Belts                     Jul  7
        J1906+0746             ACIS-I       Jul  8
        3C268.1                ACIS-S
        4U0512-401NGC185       HRC-S  LETG  Jul  9
        SN2013df               ACIS-S       Jul 10
        GMBCGJ165.03085+02.    ACIS-I
        Radiation Belts
        Mrk0810                ACIS-S
        PSRJ0358+5413          ACIS-I       Jul 11
        Vega                   HRC-S        Jul 12
        Vega                   HRC-I
        LSIV-121               HRC-I
        PSRJ1741-2054          ACIS-S
        IRASF17138-1017        ACIS-S
        Radiation Belts                     Jul 13
        RXJ0812.4-3114         ACIS-S
        ABPic                  ACIS-S
        4U0512-401NGC185       HRC-S  LETG


All spacecraft subsystems continued to support nominal operations.

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